Record global glacial melt

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"Record global glacial melt"

Record Glacier Thinning Means No Time to Waste on Agreeing New International Climate Regime,” said the UN Environment Programme (UNEP) on Sunday.

That statement is based on the data of the World Glacier Monitoring Service (WGMS), which “has been tracking the fate of glaciers for over a century. Continuous data series of annual mass balance, expressed as thickness change, are available for 30 reference glaciers since 1980.” Here’s the mean annual specific net balance:

glacier-balance.jpg

“The Service calculates thickening and thinning of glaciers in terms of ‘water equivalent’. The estimates for the year 2006 indicate that further shrinking took place equal to around 1.4 metres [1400 mm] of water equivalent compared to losses of half a metre in 2005.”

Prof. Dr. Wilfried Haeberli, Director of the Service said:

The latest figures are part of what appears to be an accelerating trend with no apparent end in sight…. This continues the trend in accelerated ice loss during the past two and a half decades.”

I know what you’re thinking: “Trend? No end in sight? But Dr. Haeberli, everybody knows the globe is cooling, and the apparent warming is just the urban heat island effect plus lousy temperature-recording stations.” As Dr. Haeberli might reply, if he had Jon Stewart’s sensibility, “Damn you, 30 reference glaciers!”

Why should we care about a bunch of melting glaciers?

Achim Steiner, UN Under-Secretary General and Executive Director of UNEP (which funds WGMS) explains:

“Millions if not billions of people depend directly or indirectly on these natural water storage facilities for drinking water, agriculture, industry and power generation during key parts of the year. There are many canaries emerging in the climate change coal mine. The glaciers are perhaps among those making the most noise and it is absolutely essential that everyone sits up and takes notice….

“The litmus test will come in late 2009 at the climate convention meeting in Copenhagen. Here governments must agree on a decisive new emissions reduction and adaptation-focused regime. Otherwise … like the glaciers, our room for manoeuvre and the opportunity to act may simply melt away,” he added.

Is he comparing us to glaciers using a simile? How could we be anything like huge blocks of ice that move really, really, really slowly?

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5 Responses to Record global glacial melt

  1. John Mashey says:

    I also recommend the Swiss Glacier website, for example, http://glaciology.ethz.ch/messnetz/lengthvariation.html , which is a very well-organized website with summaries, details of individual glaciers, pictures, in English, French, or German. The actual datasets are provided as well.
    Here’s a good summary:
    http://glaciology.ethz.ch/messnetz/glacierlist.html ,

    and a good example, the Grosser Aletsch [the longest there]:
    http://glaciology.ethz.ch/messnetz/glaciers/aletsch.html , whose detailed data is:
    http://glaciology.ethz.ch/messnetz/data/aletsch.html

    Longer glaciers take longer to react, and a nice thing with glaciers is that time series of their lengths are automatically smoothed. Of course, glacier lengths depend ion precipitation, not just temperature.
    ===========================================
    Also, they have interesting other records of the past from drawings, historical finds, nice archaeology. Here’s a very detailed example:

    See “Glacier and lake-level variations in west-central Europe over the last 3500 years” [1]. Figures 2 (Aletsch, Gorner and Lower Grindelwald) and 5 (Aletsch + lakes) are particularly useful. From eyeballing the chart, it wouldn’t claim that the current retreat is noticeably slower or faster than the previous ones, although it’s clearly retreating faster than it was ~1900, from [9] and [10].

    Although glacier mass balance is certainly not a perfect direct proxy for temperature (since precipitation matters), it is still very useful, As mentioned in [1], glaciers offer helpful time-filtering effects, i.e., longer glaciers don’t notice quick transients, like volcanic eruptions. They say Aletsch has a reaction time of about 24 years, and a response time of 50-100 years. I.e., if you suddenly raised the temperature and kept it there, it would take Aletsch a while to even notice, and then much longer before it shrank enough to get back into equilibrium. Thus, they say “The present-day position of the glacier front is therefore a reflection of the climactic conditions of past decades.” From the Swiss site above, it looks like Aletsch started showing a bigger responce around 2000, i.e., from warming starting in 1976, which fits OK.

    There is very strong known data, plus Ruddiman’s hypotheses [3, 4], that offer reasonable explanations for most of these glacier gyrations, some of which are natural, and some of which are virtually certain to be anthropogenic. In some ways, the long-term Swiss glacier gyrations are among the strongest data we have for supporting anthropogenic influences before the current AGW, and of course, the last 100 years of data show AGW’s fingerprints. A good discussion by a Swiss author can be found in[5].

    In general, typical summer solar insolation (which drives glacier retreat if above some threshold) peaked about 10,000 years ago, and is still going down (Milankovitch cycles), i.e., why we’ve had cyclic ice ages for a while. There are of course 11-year (small) jiggles from sunspot cycles, and occasionally sunspots go away (Maunder Minimum), but the general long-term temperature trend should be downward, for a while, with jiggles. Specifically, typical Summer solar insolation is lower than it was 3,500 years ago [putting together [3], Fig 1 and [1], Figure 5.],

    There are natural reasons for some jiggles. There are anthropogenic reasons for others[i.e., the plague part of Ruddiman’s hypotheses to help cause coolings pre- and post- MWP]. Right now, the large anthropogenic CO2 effect is strong enough to overpower most jiggles, and that effect is clearly seen in Aletsch, especially with the effect since 1950. [Some of the earlier rise is thought to be due to increase in solar irradiance, which then leveled off a while back.]

    In [1], they describe “periods when glacier size was similar or smaller than it is today.” Aletsch:
    1350BC-1250BC: ~1000m shorter than today
    200BC-40AD: about same as today, or maybe somewhat shorter (Roman optimum)
    750AD-1000AD (or so): about same as today (MWP)

    If you see Figure 13.1 in [4], those periods line up pretty well with periods of good health & growing populations.

    Three of the big advances in Aletsch, peaking at 600AD, 1369AD, 1666AD, 1859AD) mostly follow major pandemics ([4], p. 132. It’s worth checking column “Census.gov” of [8], for periods when populations drop or are flat.

    Correlation is not causation, and I certainly wouldn’t ascribe all of these effects to humans, but they are certainly suggestive of spikey effects that happen on the necessary timescales. Read [4] for the detailed discussion of mechanisms to connect pandemics with colder temperatures, possibly explaining the some of the otherwise puzzling ice-core CO2 gyrations [3] Figures 7 & 10.

    Roughly, one might summarize Ruddiman’s second hypothesis as: “Growing populations cleared forests, burned wood, and when large enough, more or less canceled or slowed the natural cooling trend. Major pandemics caused subsistence farms to return to forest, absorbing CO2 and lowering the temperature.”

    Hence, even knowing that [8] has some wild guesses, one compares with Aletsch:
    500BC-1AD: large population growth [retreat]
    1AD-200AD: drop [stable]
    200AD-700AD: drop/flat [slow advance, then faster]
    700AD-1200AD: big rise [fast retreat, then stable]
    [then, LIA, fast jiggles in population, fast jiggles in glaciers, with confounding factors of various solar Minima. I don’t know if these population estimates include the effects of the massive die-off of Native Americans [11] … but it is somewhat ironic if the diseases caught from early European settlers (a) caused a Native American (b) die-off that helped drop the temperature during the Little Ice Age, which caused grief in Europe, including migration from Switzerland (c) to the US.

    Figure 5 of [1] shows that after earlier steep retreats, Aletsch decelerated, and then they think it stayed in a small size range for hundreds of years [i.e., Roman warming period & MWP]. If understand [1] Fig 5 right, the last data was 2002, and it’s gone down ~250m since then … which is quite interesting, given:

    a) The lag times described by the authors, so that Aletsch is not yet responding to the last decades’ strong temperature rises.

    b) As noted earlier, typical summer solar insolation should be lower than it was 3,500 years ago, so that it should be colder. One would expect Aletsch to be longer than it was 3,500 years ago [which it seems to be], and slowly advancing….

    c) But instead, it is plunging rapidly. I think the last data in [1] was 2002, in which case the glacier has already retreated another 250m. With another 750m retreat, Aletsch will hit the bottom of the 3,500-year chart in [5], probably sometime between 2020 and 2025, assuming no acceleration. Then it will keep retreating … for a long time.

    Barring another Maunder Minimum, a nuclear war, a really major pandemic, based on straightforward GHG physics, and assuming even conservative temperature rises, I’d say the Aletsch is headed into completely off-the-chart retreat over this century, with the main human-controlled variable being how far off the chart it goes. Fortunately for Switzerland, this isn’t such a catastrophic thing, unlike high temperatures, low rainfall, and (slower) sea level rise are for some others.

    Fortunately, I’m sure the Swiss will continue to keep fine temperature records, as these things are really quite helpful!

    [1] Holzhauser, Magny, Zumbuhl http://www.unige.ch/forel/PapersQG06/Holzhauser2005.pdf

    [2]
    http://glaciology.ethz.ch/messnetz/

    [3] William Ruddiman, “The Anthropogenice Era Began Thousands of Years Ago.” 2003
    http://stephenschneider.stanford.edu/Publications/PDF_Pap
    (maybe start with the Wikipedia entry:
    http://en.wikipedia.org/wiki/Plows,_Plagues_and_Petroleum
    but it is well worth getting the main article, as it has information that does not show up in the book.]

    [4] William Ruddiman, “Plows, Plagues, and Petroleum” [2005, book, well worth having].

    [5] Wallace Broecker, Thams Stocker, “The Holocene CO2 Rise: Anthropogenic or Natural”.
    http://www.climate.unibe.ch/~stocker/papers/broecker06eos.pdf, Part of an ongoing debate with Ruddiman, others are mentioned in Wikipedia.

    [6] Fritz Gassmann. Seven Clues to the Reality of Global Warming,
    http://people.web.psi.ch/gassmann/greenhouse/seven-clues-

    [7] T Crowley, “Causes of Climate Change Over the Past 1000 Years” [2000], used in [3].
    http://www.ncdc.noaa.gov/paleo/pubs/crowley.html

    [8] World Population Estimates
    http://en.wikipedia.org/wiki/World_population_estimates

    [9] http://glaciology.ethz.ch/messnetz/glaciers/aletsch.html

    [10] http://glaciology.ethz.ch/messnetz/data/aletsch.html

    [11]
    http://en.wikipedia.org/wiki/Population_history_of_Americ

    Some of the detailed (as usual, meticulous) Swiss records here go back to 1860, i.e., well before people were thinking much about AGW.

  2. Mauri Pelto says:

    The Swiss cite referenced above is the most detailed for glacier to glacier terminus change. The WGMS record of glacier mass balance has remarkably uniform results over the years from individual glacier, yielding the large cumulative negative balance. The response time is a crucial item, there is the initial response time 24 years for Aletsch and the ovrerall response time, which is the time for a glacier to complete 2/3 of its adjustment to a climate change. An important point is identifying which glaciers are in disequilibrium and will disappear versus those who can retreat to a new point of equilibrium, at least with present climate. The explanation of this distinction and the record of individual glaciers in North America and the methods used in individual nations to compile the WGMS mass balance record is noted at:

    http://en.wikipedia.org/wiki/Glacier_mass_balance
    The results of the most extensive mass balance program in North America are at:
    http://www.nichols.edu/departments/Glacier/mb.htm
    and for the longest record in North America note:
    http://www.nichols.edu/departments/Glacier/Lemon.html

  3. David B. Benson says:

    John Mashey and Mauri Pelto — Thank you for the informative, linked-filled posts!

  4. John Mashey says:

    Thanks; Mauri is the expert, I just have Swiss ancestors.

  5. Lynne says:

    true or false, glaciers worldwide are shrinking almost one third in over all size?